Metrohm 838 Advanced Sample Processor

2.8 Dosing and liquid handling
62 Metrohm 838 Advanced Sample Processor, Operation
Exchanging Dosing unit
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Example:
DOS: 1.2 : release mL Default port = 2
This command can be used before exchanging a Dosing unit to fill the
cylinder via the given port. In this way, for example, air can be aspi-
rated via Port 4.
After the cylinder has been filled the stopcock will move to Port 2. The
dosing drive can then be removed from the Dosing unit.
Preparing the Dosing unit
Example:
DOS: 1.* : prepar. mL Default port = 1
In order to prepare a Dosing unit for use a complex procedure is
started: first the cylinder contents are ejected via the given port, then
the volume of the filling tubing is drawn in and ejected again via the
given port. All the connected pieces of tubing are then filled bubble-
free (tubing length > 0 mm) and finally the cylinder is filled again.
The volumes of the connected pieces of tubing (calculated from length
and diameter) are taken into account during the whole procedure.
Automatic emptying
44
Example:
DOS: 1.4 : empty mL Default port = 1
Automatically emptying the Dosing unit takes place according to a
complex procedure: first the cylinder contents are ejected via the given
port, the ejection tubing is then briefly rinsed with reagent from the fill-
ing tubing and then all the pieces of tubing are emptied in sequence.
Air is always aspirated via the drain port (default: Port 4) for emptying.
The volumes of the connected pieces of tubing (calculated from length
and diameter) are taken into account during the whole procedure.